SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c6a2eedd677481588afc776c4182500ab923544a52b135b4256581aebe1a887' 
  AND token = 'QfBbeC/oWSSO7jEc99+2xbQD1cHWEnc221oOMMMwhsQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}